Fastener assembly with improved temporary attachment layer

ABSTRACT

An elongate fastener assembly comprising a flexible polymeric backing strip from which project a multiplicity of headed stems adapted to engage loops on materials pressed against the heads, and an open porous permanent attachment layer attached to the surface of the backing strip opposite the stems which has sufficient open area to receive foam to permanently attach the fastener assembly to a foamed article. The fastener assembly has a temporary attachment layer comprising granular ferromagnetic material in a polymeric binder sandwiched between the backing strip and the permanent attachment layer which is adapted to be attracted by magnets to temporarily hold the fastener assembly in position during a foaming process, and has a heat shrinkable film cover means overlaying the heads attached to the edges of the backing strip that will shrink transversely to expose the heads upon the application of heat below 125° C.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.629,330 filed July 10, 1984, abandoned.

TECHNICAL FIELD

The present invention relates generally to fasteners, and particularlyto the type of fastener used to attach upholstery fabrics with loops ontheir back surfaces to foam seat cushions.

BACKGROUND ART

A recently developed fastener assembly used to attach upholstery fabricswith loops on their back surfaces to foam seat cushions of the type usedin automobiles includes a polymeric backing strip, a multiplicity ofstems each secured at one end to and projecting from a first surface ofthe backing strip and having enlarged heads at their ends opposite thebacking strip adapted to engage the loops on the upholstery materialwhen the material is pressed against the heads, and an open porouspermanent attachment layer attached to the surface of the backing stripopposite the stems. The fastener assembly is placed with its headsadjacent to the inner wall of a seat mold, a seat cushion is foamed inthe mold, and the permanent attachment layer has sufficient open areasto afford movement of foam into it to permanently attach the fastenerassembly to the newly foamed seat cushion.

This fastener assembly also typically includes a strip of steelsandwiched between the backing strip and the permanent attachment layerthat provides means by which the fastener assembly can be magneticallyheld in a predetermined location against the inner wall of the mold inwhich the seat cushion is foamed. While the steel strip affords enoughmagnetic attraction to hold the strip in place prior to foaming, itpresents a problem in a subsequent heat cure process during which thefoam seat cushions removed from the mold are heated to about 125° C.(250° F.). This temperature causes longitudinal shrinkage in thepolymeric backing strip, which shrinkage does not occur in the steelstrip. Thus pieces of the thin steel strip either buckle within thefastener assembly giving it an uneven contour, or project from the endsof the fastener assembly and can cut the cushion, or the overlayingfabric, or even a person handling or sitting on the seat.

Additionally this fastener assembly has an elongate film layer overlyingthe heads and having longitudinal edge parts attached to the edges ofthe backing strip. This layer is positioned between the heads and thewall of the mold during the foaming process to prevent foam from movinginto the spaces around the heads and stems which would reduce theability of the heads to subsequently engage loops on the fabric. Thisfilm is adapted to then expose the heads during the heat cure processfor the cushion by being meltable at a temperature below 125° C. Whilesuch melting exposes the heads and stems, it also coats them with thefilm material which can detract from the holding ability of the heads.

DISCLOSURE OF THE INVENTION

The present invention provides an elongate fastener assembly generallyof the type described above which has a magnetically attractabletemporary attachment layer that will not significantly project from theends of the fastener assembly or cause it to buckle after the fastenerassembly has undergone the heat cure process for the cushion.

According to the present invention there is provided an elongatefastener assembly comprising a flexible polymeric backing strip, amultiplicity of stems

each secured at one end to the backing strip and projecting generallynormally to one of its major surfaces and having enlarged heads at theirends opposite the backing strip adapted to engage loops on materialspressed against the heads, and an open porous permanent attachment layerattached to the major surface of the backing strip opposite the stemswhich has sufficient open area to afford movement of foam into thepermanent attachment layer to permanently attach the fastener assemblyto a foamed article.

The fastener assembly also has a temporary attachment layer comprisingferromagnetic material sandwiched between the second major surface ofthe backing and the attachment layer, which temporary attachment layeris adapted to be attracted by magnets to temporarily hold the fastenerassembly in position during the foaming process. In the presentinvention this temporary attached layer is improved in that it comprisesa polymeric bonding material (e.g. comprising vinyl or an elastomer)containing ferromagnetic particles (e.g. iron), which bonding materialexhibits essentially the same shrinkage as the backing strip when theassembly is exposed to temperatures around 125° C. so that thetemperatures resulting from the heat cure process for seat cushions willnot cause a substantial relative change in length between the backingstrip and the temporary bonding layer and will not cause the backingstrip to buckle.

Additionally the elongate fastener assembly includes an elongate filmcover means overlying the heads and having longitudinal edge partsattached along the sides of the backing strip, which film cover means isadapted to expose the heads upon the application of heat. As is claimedin U.S. patent application Ser. No. 629,331 filed July 10, 1984, thisfilm cover means is improved in that it comprises two longitudinal filmportions, each portion being sufficiently heat shrinkable in thetransverse direction so that upon application of such heat, it willshrink towards the edge parts to expose the heads. This film layer meanscan comprise either a single longitudinal sheet of film longitudinallyperforated generally along its center line to define the two portions sothat the sheet separates along the perforations to afford transverseshrinking of the portions; or can comprise two separate sheets of filmhaving overlapping portions opposite their edge parts.

BRIEF DESCRIPTION OF DRAWING

The present invention will be more thoroughly explained with referenceto the accompanying drawing in which like numbers refer to like parts inthe several views, and wherein:

FIG. 1 is a perspective fragmentary view of a fastener assemblyaccording to the present invention;

FIG. 2 is a reduced sectional view of the fastener assembly of FIG. 1being magnetically held in a fragment of a mold used to mold seatcushions;

FIG. 3 is a reduced sectional view of the fastener assembly of FIG. 1shown attached to a foam cushion with a film layer of the assemblyshrunk away from over heads on the fastener by a heat cure process forthe cushion; and

FIG. 4 is an end view of an alternate embodiment of the fastenerassembly according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 of the drawing, there is shown an elongatefastener assembly according to the present invention, generallydesignated by the reference numeral 10.

Generally, like the prior art fastener assemblies, the elongate fastenerassembly 10 comprises (1) a flexible polymeric backing strip 12 havingfirst and second major surfaces 14 and 16; (2) a multiplicity of stems18 each secured at one end to the backing strip 12, projecting generallynormally from its first surface 14 of the backing strip 12, and havingenlarged heads 20 at their ends opposite the backing strip 12 adapted toengage loops on materials pressed against the heads; (3) an open porouspermanent attachment layer 22 attached to the second major surface 16 ofthe backing strip 12 by a layer of adhesive 23, which permanentattachment layer 22 has sufficient open area to afford movement of foaminto it to permanently attach the fastener assembly to a foamed article;(4) a temporary attachment layer 24 comprising ferromagnetic materialsandwiched between the second major surface 16 of the backing strip 12and the permanent attachment layer 22, which temporary attachment layer24 is adapted to be attracted by magnets to temporarily hold thefastener assembly in position during a foaming process; and (5) anelongate film cover means or film portions 30 overlying the heads 20 andhaving longitudinal edge parts 26 attached along the edges of thebacking strip 12 by bonding layers 31, which film layer means is adaptedto expose the heads 20 upon the application of sufficient heat.

Unlike the prior art fastener assemblies of this type, however, thetemporary attachment layer 24 of the strip material 10 is improved inthat it comprises ferromagnetic particles dispersed in a polymericbonding material, which bonding material may or may not have generallythe same coefficient of themal expansion as the backing strip 12, but ineither event exhibits essentially the same shrinkage as the backingstrip 12 when the backing strip 12 shrinks (apparently due either tostress relaxation or compression) during exposure to temperatures around125° C. While the temporary attachment layer 24 appears to shrink withthe backing strip 12, we theorize that it may be compressed by thebacking strip 12 without distorting the fastener assembly 10. Thus suchtemperatures which are employed in the seat forming process will notcause a substantial relative change in length between the backing strip12 and the temporary bonding layer 24.

Also, unlike the prior art fastener assemblies of this type, the filmcover means in the fastener assembly 10 according to the presentinvention is improved in that it comprises two longitudinal filmportions 30, each portion 30 being sufficiently heat shrinkable in thetransverse direction so that upon application of said heat in the seatforming process it will shrink towards the edge parts 26 by which it isfastened to expose the heads 20.

As illustrated in FIGS. 1 and 2, the film cover means comprises a singlelongitudinal sheet of film having perforations 32 generally along itscenter line to define the two portions 30; the sheet being separablealong the perforations 32 to afford transverse shrinking of each portion30, to the position shown in FIG. 3. The bonding layers 31 attaching theedge parts 26 of the sheet of film to the permanent attachment layer 22may be extensions of the layer of adhesive 23 as described in our U.S.patent application Ser. No. 629,330, but alternatively, as illustrated,may be thin layers of pressure-sensitive adhesive or hot melt adhesivewhich afford a thinner and more flexible fastener assembly; the mostimportant aspect of those bonding layers 31 being that they firmlyanchor the edge parts 26 of the sheet of film when it is heat shrunkfrom over the heads 20.

Alternatively, as illustrated for an alternate embodiment for a stripmaterial 50 according to the present invention shown in FIG. 4 (whereinall parts of the strip material 50 that are the same as the parts of thestrip material 10 are identified by the same reference numerals to whichhave been added the suffix "a") the film cover means can comprise twoseparate sheets 52 of the film having overlapping portions 53 oppositeedge parts 54 by which the sheets are attached along the longitudinaledges of the backing strip 12a by the bonding layers 31a.

Preferably the backing strips 12 or 12a with the attached stems 18 or18a and heads 20 or 20a are made in accordance with U.S. Pat. No.4,454,183 (incorporated herein by reference), and particularly inaccordance with the embodiment described with references to FIG. 7 ofthat patent which is made by a method described in U.S. Pat. No.4,290,832 (also incorporated herein by reference). Alternatively,however, an integrally molded structure providing a backing strip, stemsand heads could be used.

The permanent attachment layer 22 or 22a is preferably of fine denierpolypropylene fibers (e.g. 3 to 4 denier fibers 7.6 to 10 centimeters (3to 4 inches) long) that have been formed into a nonwoven mat and needledtogether to provide a strong porous structure (e.g. 0.2 centimeter(0.080 inch) thick by 4.5 centimeters (1.75 inch) wide) with asubstantial percentage of open area to permit the inflow of foam.

As one example, the ferromagnetic material in the temporary attachmentlayer 24 or 24a may be iron particles, such as the gritty iron particlescommercially designated type T-50+100 commercially available fromPeerless Metal powder Company, Detroit, Mich., and the polymeric bondingmaterial in which the iron particles are dispersed may be formed from amixture of vinyl (which has about the same coefficient of thermalexpansion as the backing strip), plasticizer and solvent such as thefollowing mixture wherein all parts are parts by weight. A dry mixtureis made from 100 parts of an emulsion grade polyvinyl chloride resin, 16parts of butyl methacrylate acrylic resin, 37 parts of a compatiblepolymeric plasticizer and 5 parts of a compatible heat stabilizer. Onepart of this dry mixture is then combined with 5 parts of ironparticles, and that combination is mixed with sufficient parts of asolvent consisting of 46% xylene, 34% diisobutyl ketone and 20% mineralspirits to produce a coating mixture having a viscosity of about 4000centipose. The coating mixture is coated on a suitable release liner,dried in an oven with zones of increasing temperature from about 65° to205° C. and slit to provide a temporary attachment layer about 0.013 to0.05 centimeter (0.005 to 0.020 inch) thick and about 1.3 centimeter(1/2 inch) wide.

As another currently preferred example, the ferromagnetic material inthe temporary attachment layer 24 or 24a may be iron particles, such asthe gritty iron particles commercially designated type T-100commercially available from Peerless Metal Powder Company, Detroit,Mich.; and the polymeric bonding material in which the iron particlesare dispersed may be formed from a mixture of an A-B-A type copolymerelastomer and solvent such as the following mixture wherein all partsare parts by weight. A mixture is made from 100 parts of the A-B-A typecopolymer elastomer commercially designated "Krayton 1101" and availablefrom Shell Chemical Co., 300 parts tolulene and 1000 parts of ironparticles. That mixture is coated on a suitable release liner, dried inan oven with zones of increasing temperature from about 65° to 95° C.and slit to provide a temporary attachment layer about 0.036 to 0.04centimeter (0.014 to 0.016 inch) thick and about 1.3 centimeter (1/2inch) wide. Such a temporary attachment layer 24 or 24 a does not havethe same coefficient of thermal expansion as the backing strip 12 or12a, but apparently has sufficient voids, is sufficiently elastic, andadheres sufficiently to the backing strip 12 or 12a to be compressed byshrinkage of the backing strip 12 or 12a when it is exposed totemperatures around 125° C. so that the fastener assembly 10 or 50 willnot be distorted by the presence of the temporary attachment layer 24 or24a.

Alternatively, it is expected the temporary attachment layer could beformed through the use of hot melt mixing equipment, such as anextruder, or the layer of adhesive 23 or 23a could be used to hold theiron particles in place, or the iron particles could be distributed in amatrix of fused polymeric material such as a polyolefin (which wouldhave about the same coefficient of expansion as the backing strip 12 or12a) and produce similar results.

The layer of adhesive 23 or 23a that bonds the backing strip 12 or 12a,temporary attachment layer 24 or 24a and permanent attachment layer 22or 22a together is preferably of a thermoplastic resin of the polyolefintype which can be applied to these parts between nip rollers, one ofwhich rollers is notched to receive the heads 20 or 20a and stems 18 or18a.

Strips (not shown) of a foam material (e.g. about 0.08 centimeter (1/32inch) thick, 1 centimeter (3/8 inch) wide strips of 2.7 kilogram (6pound) polyurethane foam) may optionally be adhered in positionsflanking the backing strip 12 or 12a between the bonding layers 31 or31a and the sheet portions 30 or sheets 52 to provide additionalgasketing for the fastener assembly 10 or 50 against the walls of amold, should that be desired.

The sheet portions 30 (FIG. 1) or sheets 52 (FIG. 4) of film thatprovide the film cover means are preferably formed of a biaxiallyoriented prestressed polyvinyl chloride film 0.0025 centimeter (0.001inch) or less thick, such as that commercially designated "Krystal Tite"shrink film type T144 or Type T-111 which film can be oriented so thatit will shrink transversely of the fastener assembly 10 by about 60%when heated to less than about 125° C. This film, when unrestrained,would also shrink longitudinally of the strip assembly by about 40%,however attachment of the film along the backing strip 12 or 12a by thebonding layers 31 or 31a will prevent such shrinkage during such heatingwithout causing buckling of the fastener assembly 10.

In use the fastener assembly 10 (as illustrated in FIG. 2) is positionedwith the film portions 30 against the wall of a mold 40 in which a seat42 is to be foamed with the stems 18 and heads 20 positioned in a groove44 in that wall adapted to receive them, and the fastener assembly 10temporarily held in place in the groove 44 by magnetic attractionbetween the iron particles in the temporary attachment layer 24 and asource of magnetism such as a magnet 46 in the wall of the mold 40. Themold 40 is then closed and filled with foam to form the seat 42, withthe foam entering the porous permanent attachment layer 22 to secure thefastener assembly 10 in the seat with its heads 20 and their coveringfilm portions 30 at the outer surface of the seat 42. During formationof the seat the film portions 30 insure that foam does not flow aroundthe stems 18 and under the heads 20 to restrict their subsequentengagement with loops on a fabric covering for the seat 42 (not shown).After the foam seat 42 is formed, it is removed from the mold 40 andsent through a heat curing process at about 125° C., during whichprocess the film portions 30 separate at the perforations 32 and shrinkback from over the heads 20 to expose them for subsequent engagementwith the loops on the fabric used to cover the seat 42 as is shown inFIG. 3. The fastener assembly 10 will also shrink including in thelongitudinal direction, however, the temporary attachment layer 22 andbacking strip 12 will shrink or be compressed at about the same rate,thereby precluding any projection of the temporary attachment layer 24from the ends of the backing strip 12 or bending of the backing strip 12as would occur if the temporary attachment layer 24 were of solid metal.

We claim:
 1. In an elongate fastener assembly comprising a polymericbacking strip having first and second major surfaces;a multiplicity ofstems each secured at one end to said backing strip, projectinggenerally normally to the first surface of said backing strip, andhaving enlarged heads at their ends opposite said backing strip adaptedto engage loops on materials pressed against said heads; an open porouspermanent attachment layer atached to the second major surface of saidbacking strip, said permanent attachment layer having sufficient openareas to afford movement of foam into said permanent attachment layer topermanently attach said fastener assembly to a foamed article; and atemporary attachment layer comprising ferromagnetic material sandwichedbetween the second major surface of said backing and said attachmentlayer, said temporary attachment layer being adapted to be attracted bymagnets to temporarily hold said fastner assembly in position during thefoaming process; the improvement wherein the temporary attachment layercomprises ferromagnetical particles dispersed within a polymeric bondingmaterial, said bonding material exhibiting essentially the sameshrinkage as said backing strip when said fastener assembly is exposedto temperatures around 125° C., so that the temperatures resulting fromthe foaming process will not cause a substantial relative change inlength between the backing strip and the temporary attachment layer. 2.An elongate fastener according to claim 1 wherein said binder comprisesvinyl material and said ferromagnetic material is iron particles.
 3. Inan elongate fastener assembly comprising a polymeric backing striphaving first and second major surfaces:a multiplicity of stems eachsecured at one end to said backing strip, projecting generally normallyto the first surface of said backing strip, and having enlarged heads attheir ends opposite said backing strip adapted to engage loops onmaterials pressed against said heads; an open porous permanentattachment layer attached to the second major surface of said backingstrip, said permanent attachment layer having sufficient open areas toafford movement of foam into said permanent attachment layer topermanently attach said fastener assembly to a foamed article; and atemporary attachment layer comprising ferromagnetic material sandwichedbetween the second major surface of said backing and said attachmentlayer, said temporary attachment layer being adapted to be attracted bymagnets to temporarily hold said fastener assembly in position duringthe foaming process; the improvement wherein the temporary attachmentlayer comprises ferromagnetical particles dispersed within a polymericbonding material, said bonding material having generally the samecoefficient of thermal expansion as said backing strip and exhibitingessentially the same shrinkage as said backing strip when said fastenerassembly is exposed to temperatures around 125° C., so that thetemperatures resulting from the foaming process will not cause asubstantial relative change in length between the backing strip and thetemporary attachment layer.
 4. An elongate fastener according to claim 3wherein said binder comprises vinyl material and said ferromagneticmaterial is iron particles.